Myocarditis with multinucleated giant cells detected in biopsy specimens

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Abstract
A 42‐year‐old woman was transferred to our hospital for evaluation of bradycardia with a complete atrioventricular block. Her pulse was 41 regular beats/min with blood pressure 166/92 mmHg. There were no skin lesions, edema, or lymphadenopathy. The white blood cell count was 6300/mm3. The serum glutamic oxaloacetic transaminase was 21 IU and creatine phosphokinase was 34 IU. C‐reactive protein was negative. The level of serum angiotensin converting enzyme was slightly increased at 25.8 IU/1/37.0°C (normal range: 7–24.0). Chest radiography showed congestive heart failure with a cardiothoracic ratio of 54%. There was no bilateral lymphadenopathy or fibrous changes during her clinical course. The coronary arteries were completely normal angiographically. Left ventriculograms revealed slight hypokinesis and dilatation (end‐diastolic volume index of 112 ml/m2, ejection fraction of 53%). Left ventricular end‐diastolic pressure was slightly abnormal at 16 mmHg. Two right and two left ventricular endomyocardial biopsies were performed. Right ventricular biopsy demonstrated edematous tissue and a slight mononuclear cell infiltration with little fibrosis. Left ventricular specimens showed an extensive area of fibrosis, with large, multinucleated giant cells with an asteroid body and chronic inflammation without epitheloid cells. The less affected areas of another specimen showed mild interstitial fibrosis and degenerative myocytes with vacuolation, and some multinucleated myocytes without an asteroid body were present. This case was diagnosed as cardiac sarcoidosis rather than idiopathic giant cell myocarditis. The patient has been implanted with a permanent pacemaker. This case is of clinical interest from three aspects: (1) the specific lesion in the myocardium was confirmed by examination of several biopsy specimens; (2) the multinucleated giant cells are of two sizes: the larger cells, having an asteroid body in the cytoplasm, appear to be derived from histiocytes, and the smaller cells are considered to be derived from myocyte; (3) the patient is doing well with a permanent pacemaker and requires no immunosuppressive therapy at one and half years later.